12 Principles of Animation

Source: ui-skills.com.

Disney animators codified these principles in the 1930s to make drawings feel real. We use them to make pixels feel human. The problems are surprisingly similar.

When to Apply

Reference these guidelines when:

Adding motion to UI components
Reviewing animation quality and feel
Designing micro-interactions and feedback
Making interfaces feel more alive and responsive
Deciding what should (and shouldn't) animate

Principles Overview

#	Principle	Web Application
1	Squash and Stretch	Convey weight and elasticity in morphing elements
2	Anticipation	Prepare users for what comes next (wind-up before action)
3	Staging	Direct attention through sequential animation
4	Straight Ahead & Pose to Pose	Define keyframes, let browser interpolate
5	Follow Through & Overlapping	Use springs for organic overshoot-and-settle
6	Slow In & Slow Out	Apply easing curves for natural acceleration
7	Arcs	Add curved paths for organic movement
8	Secondary Action	Reinforce primary actions with subtle flourishes
9	Timing	Keep interactions under 300ms, be consistent
10	Exaggeration	Amplify motion for emphasis (sparingly)
11	Solid Drawing	Use perspective, shadows, and depth
12	Appeal	The sum of all techniques applied with care

Quick Reference

1. Squash and Stretch

Digital objects don't have physics, so we fake it. Subtle deformation conveys weight—but don't overdo it or professional software becomes a cartoon.

2. Anticipation

Give cues before major actions. Pull-to-refresh hints, buttons that compress before sending. Reserve for moments that matter—too many wind-ups make apps feel sluggish.

3. Staging

Guide the eye through sequential animation. Dim backgrounds, focus on important elements. Direct attention like a film.

4. Straight Ahead & Pose to Pose

Focus on key poses: start state, end state, maybe a midpoint. Context menus animate on exit only—entrance animation compounds into irritation.

5. Follow Through & Overlapping

Nothing moves as a single rigid unit. Springs add organic overshoot-and-settle that easing curves can't replicate. But too much stagger makes interfaces feel slow.

6. Slow In & Slow Out

ease-out: Entrances (arrive fast, settle gently)
ease-in: Exits (build momentum before departure)
ease-in-out: Deliberate movements

7. Arcs

Curved paths feel inevitable, like water finding its level. Best for hero moments and playful interactions. Utilitarian interfaces work fine with straight lines.

8. Secondary Action

Flourishes supporting the main action—sparkles after success, sound effects on impact. Think games: they combine sound and visual effects for impact.

9. Timing

Keep interactions under 300ms. Be consistent—if one button animates at 200ms, all buttons should. Define timing scales early, reuse everywhere.

10. Exaggeration

Push past physical accuracy to make points land harder. Use sparingly for onboarding, empty states, confirmations, or errors.

11. Solid Drawing

Shadows suggest depth. Layering implies hierarchy. CSS perspective gives 3D transforms actual depth.

12. Appeal

The difference between software you tolerate and software you love. Not one technique—the sum of all techniques applied with care and taste.

Key Guidelines

Balance: Too much animation turns professional software into a cartoon
Consistency: Define timing scales early, reuse everywhere
Purpose: Great animation is invisible—users think "this feels good"
Restraint: Not everything needs to be animated

References

The Illusion of Life: Disney Animation
Apple WWDC23: Animate with Springs
easing.dev - Easing function playground
Rauno's Invisible Details of Interaction Design